George de Mestral while walking his dog in the woods noticed that burrs tenaciously gripped his dog's fur. He replicated the junction of the burrs and the fur on two strips of fabric with one strip containing engaging members (the “hook” strip) and the other strip containing fabric loops (the “loop” side). He created the portmanteau VELCRO out of “velour” meaning looped fabric and “crochet” meaning hook.
Early versions of the hook-and-loop fasteners were woven and exhibited a “scratchy” hook side that consisted of many randomly oriented, nylon-coated woven hooks cut eccentrically to allow the hooks to engage the many loops on the loop side. The hook side was scratchy and annoying to the touch, clung to unintended materials, and possessed a Standard Velcro Peel Strength (SVPS).
Decades passed and a wide variety of engineered hooks (molded or extruded in an essentially planar plastic) arose to supplement the existence of the standard hook-and-loop fastener. Most of these new hook shapes resembled the crests of waves, others resembled mushroom caps, and yet others possessed novel shapes (e.g. bulbous parallelograms on a stick, anchors, etc.). The varying shapes were invented for the hook side to vary the peel strength, shear strength, cycle life, and perceived roughness to the touch, as well as reduce the likelihood of catching on unintended looped surfaces, like expensive sweaters, pantyhose, etc.
Woven hook was commonly adhered to a flexible surface by sewing the material backing of the hook strip to some other substrate (material, cloth, leather, vinyl, etc). Woven hook embodiments included many flaws: woven hook was difficult to sew and caused snags in the sewing machine thread; often the hammer of the sewing machine would deform or crush some or many of the hooks; a manufacturer had to ensure that the peel strength of the hook-and-loop system did not exceed the tensile strength of the threads anchoring the hook strip to the substrate—otherwise upon strip removal the hook strip would pull itself from threads holding it to the substrate. Comparatively speaking, the loop strip of hook-and-loop fasteners acts similar to any other rigid material; it is simple to sew, and it does not snag thread. Where perimeter sewing is insufficient to exceed the peel strength of the hook-and-loop system, the system can be anchored with grids, zig-zags, reinforcement points for large surface areas, etc. Although increasing the thread quantity substantially increases the ability of the hook-and-loop system to adhere to a backing material, excess threading may diminish the adherence between the hooks and loops.
For impenetrable and prohibitively penetrable backings such as dashboards, walls, tables, and other non-sewable objects, woven hook was backed with an adhesive that varied in tenacity depending on the manufacturer and product line. More often than not, repeated disengagement cycles would eventually cause the hook strip to peel from the substrate. Most adhesives need some sort of pressure or impact force to activate the molecules of the adhesive to adhere the molecules of the backing. For example, most shoe soles bonded to a shoe with contact cement are banged with a hammer to activate the bonds of the cement. In adhesive bonded hook-and-loop applications, one might apply force to the loop side with impunity; the hook side, however, includes more delicate structures more easily crushed, damaged, or broken. This principle applies to compressive forces exerted via pinch rollers, and many other common fabrication devices.
Considerable deliberation precedes use of hook-and-loop fasteners in design applications: the hook side is widely despised by consumers. No one wants to touch it and it ought not dangle free due to its tendency to catch and snag something of value. For example, in notebooks and briefcases the hook side was usually reserved for the flap. In the minority of times when this design was not adopted, it usually followed that the flap was intended to dangle freely. Either way, entire board rooms of designers, marketers, and product specialists would occasionally spend countless hours deciding which side would house the dreaded hook side (e.g., tablet PC hand-held cases, Palm Pilot cases, cell phone cases, clothing flaps, etc.).
For variable circumference applications such as shoe closures or neck closures for motorcycle jackets, some portion of unused hook surface will always remain exposed (i.e. unmated) on the flap side for small necks or narrow feet; or if the hook surface is placed on the non-flap side, it is often exposed for large necks and high arches, thereby catching and fraying things like scarves or woven trousers. It is often the case that no clear choice exists for placement of the hook surface and the placement of the loop surface.
Many outdoor garments use hook-and-loop closures. Laundering them is cumbersome as consumers fear mingled other garments with garments bearing hook-and-loop closures; its neighbors are in constant peril of getting snagged by the hook side. If one attempts to solve the garment mutilation problem by engaging the hook side onto its intended loop side—as in, say, a coat sleeve—then the dirty crevice formed by the fold does not get clean. Some garments, like sweaters with hook-and-loop closures, are prime candidates for mutilation should a fastened hook strip inadvertently disengage from its loop and catch the fabric of the sweater during the washing machine's agitation cycle.
Many times, the hook-and-loop closures lose their useful peel strength more rapidly than the item to which they are attached lose their utility, especially in tough garments, leather briefcases, etc. Frequently a new hook-and-loop system cannot be reattached cost effectively, rendering the entire item useless. Spent hook-and-loop systems may be characterized by a loop side frayed to present a “fuzzy” surface or severed hooks that break or become disoriented to lose their strength.
Therefore, there is a need for a fastening system that allows prolonged use of an item accommodating the fastening system, creates diversity in the closure strength of the fastening system, increases the desirability of hook-and-loop fasteners, decreases the likelihood of unintended fastening to foreign objects, minimizes assembly complexity, minimizes article cost, and that is replaceable.